Phthalocyanine series compounds are known as pigments for a long time but recently these compounds are also being watched with keen interest as the materials responding to a near infrared light source having a long wavelength.
In particular, as the materials being used for organic photoconductors of copying machines, LD printers, LED printers, etc., utilizing a light source of a long wavelength of near 800 nm, such as a semiconductor laser and light emitting diode (LED) with the recent development of electronic industry, the phthalocyanine series compounds responding to these light sources being watched with keen interest.
In the preprints, Japan Hardcopy '92, pages 153-156, 1992 Densi Shashin Gakkai (Electrophotographic Society), there is described a lecture gist entitled "Formation and Properties of Titanyl Phthalocyanine Crystals containing Diol Compound" and in the preprints, Japan Hardcopy '93, pages 659-662, 1993 Densi Shasin Gakkai (Electrophotographic Society), there is described a lecture gist entitled "Syntheses and Properties of Titanyl Phthalocyanine new Polymorphs". Also, in JP-A-5-273775 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), there is described that a diol compound having one hydroxy group at each of two adjacent carbon atoms, such as, for example, 2,3-butanediol, etc., reacts with oxytitanium phthalocyanine at an addition ratio of 1:2 to form an addition compound and the possibility capable of being used for organic photoconductors, etc., is suggested.
As the material responding to a near infrared light source, a material having a light absorption at a longer wavelength region is preferred but in the compound obtained by reacting commercially available 2,3-butanediol as it is with titanyl phthalocyanine, there are problems that the absorption wavelength is not in a sufficiently long wavelength region, etc.
Furthermore, when a steroisomer group can exist in a diol compound such as 2,3-butanediol, by such a broad concept expression, it is unknown that a phthalocyanine compound is obtained by what kind of an isomer diol and for example, an organic photoconductor using a compound obtained by performing the reaction of meso-isomer diol and oxytitanium phthalocyanine has a fault that a sufficient sensitivity is not obtained.